HRT Dangers Should have been Spotted Sooner

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HRT Dangers Should Have Been Spotted Sooner

By Amanda Gardner

HealthDay Reporter

 

 

 

FRIDAY, Feb. 27 (HealthDayNews) -- In a sort of scientific slap on

the hand, British researchers say experts should have realized the

dangers of hormone replacement therapy for women much sooner than

they did.

 

In fact, scientific research in general is fraught with problems,

say the authors of a paper in the Feb. 28 issue of the British

Medical Journal, including a lack of clear information on long-term

side effects.

 

The saga of hormone replacement therapy (HRT) is just a case in

point, they note.

 

Based primarily on observational studies alone, experts and

consumers alike came to believe HRT not only eased the symptoms of

menopause, but also lowered the risk of cardiovascular disease.

 

In 2002, however, the largest randomized trial on the subject, the

U.S. government-sponsored Women's Health Initiative (WHI) was

abruptly halted when it was found that the opposite was true: HRT

increased the risk not only of cardiovascular disease but also of

breast cancer and stroke.

 

What happened?

 

Part of it is the sheer complexity represented by hormones, one

expert notes.

 

" They affect so many different systems in the body that it's not as

clear as it might be with another kind of drug that only has one

purpose, " says Dr. Margery L.S. Gass, a professor of clinical

obstetrics and gynecology at the University of Cincinnati College of

Medicine and a WHI investigator.

 

But part of the discrepancy can be explained by the differences

between observational trials, which leave room for various types of

bias, and randomized trials.

 

" It's an important difference, " says Klim McPherson, co-author of

the British paper and a visiting professor of public health

epidemiology in the Nuffield Department of Obstetrics and

Gynaecology at Churchill Hospital in Oxford, England. " If what you

do is simply observe people who choose to take something as opposed

to people who don't choose and see what happens, that is quite

likely to be contaminated by biases. Namely, the people who take

something are different from those who don't take it. "

 

Randomized trials, on the other hand, start with a group of people

randomly assigned to receive either the intervention or a placebo,

thus eliminating this particular type of bias.

 

In the 1990s, McPherson and his colleagues examined existing trials

on HRT. " We found 200 trials of efficacy, [but] most were useless

because they didn't record any kind of side effects and many of them

didn't have proper controls, " McPherson says. " There were only 23

that were useful. "

 

Their analysis of those 23 smaller, randomized trials foreshadowed

what was to come. The conclusions, published in 1997, however, were

not well-received.

 

They then located six more trials and had to obtain a court order to

see them. " Six trials were unavailable because they weren't

published and the manufacturers refused access to these data. We had

to go to court to get access and, once again, it was confirmatory, "

McPherson says.

 

A synthesis of all this earlier data might have spared hundreds of

thousands of women the risks involved with exposure to HRT. It might

also have made the WHI trial unnecessary, the paper's authors state.

 

" What happens is that individual applications are assessed on their

own merit, " McPherson says. " Unless you pool these results, you

don't get any answers. "

 

Other experts don't agree, however. " It's very easy in retrospect,

but doing prospective, randomized trials on important health issues

is the absolute critical thing that we as a society need to do, "

says Dr. Jay Brooks, chief of hematology/oncology at the Ochsner

Clinic Foundation in New Orleans. " One of the problems in American

medicine today is that we try to rush things to judgment based on

small, selective studies. "

 

The study authors make a number of recommendations based on their

experience, namely that regulators require that all studies on

efficacy be made available and that adverse effects, even long-term

and rare ones, should be recorded and made part of the public

research record.

 

Also, McPherson adds, " studies ought to be big enough to detect rare

events and most of these weren't big enough. "

 

But even if a synthesis of smaller trials leads researchers to

certain conclusions, a large randomized trial is still warranted,

Brooks says. " There had been some previous studies that had hinted

at [cardiovascular risk with HRT], but they hadn't really been well-

designed ones that the WHI was. Everyone shot holes in the previous

studies, " he says. " We need to do the proper trials up front before

we embark on these major scientific recommendations. "

 

And even then, many mysteries often remain. " We have a lot of

unanswered questions, " says Gass. " What happens in science all the

time is something we think is going to give us a simple answer often

raises more questions. "

 

More information

 

The National Institutes of Health has more information on the

Women's Health Initiative. The U.S. Centers for Disease Control and

Prevention has more on understanding scientific research.

 

SOURCES: Klim McPherson, Ph.D., visiting professor, public health

epidemiology, Nuffield Department of Obstetrics and Gynaecology,

Churchill Hospital, Oxford, England; Jay Brooks, M.D., chief,

hematology/oncology, Ochsner Clinic Foundation, New Orleans; Margery

L.S. Gass, M.D., professor, clinical obstetrics and gynecology,

University of Cincinnati College of Medicine, director, University

Hospital Menopause and Osteoporosis Center, and immediate past

president, North American Menopause Society; Feb. 28, 2004, British

Medical Journal

 

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